<!DOCTYPE html>

































































<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="shortcut icon" type="image/x-icon" href="../../../favicon.ico" />
<title>Canvas and Drawables | Android Developers</title>
<link href="../../../assets/android-developer-docs-devguide.css" rel="stylesheet" type="text/css" />
<script src="../../../assets/search_autocomplete.js" type="text/javascript"></script>
<script src="../../../assets/jquery-resizable.min.js" type="text/javascript"></script>
<script src="../../../assets/android-developer-docs.js" type="text/javascript"></script>
<script src="../../../assets/prettify.js" type="text/javascript"></script>
<script type="text/javascript">
  setToRoot("../../../");
</script>
<noscript>
  <style type="text/css">
    html,body{overflow:auto;}
    #body-content{position:relative; top:0;}
    #doc-content{overflow:visible;border-left:3px solid #666;}
    #side-nav{padding:0;}
    #side-nav .toggle-list ul {display:block;}
    #resize-packages-nav{border-bottom:3px solid #666;}
  </style>
</noscript>
</head>
<body class="gc-documentation">

  <div id="header">
      <div id="headerLeft">
          <a href="../../../index.html" tabindex="-1"><img
              src="../../../assets/images/bg_logo.png" alt="Android Developers" /></a>
          <ul id="header-tabs" class="guide">
    
	<li id="home-link"><a href="../../../offline.html">
	
		<span class="en">Home</span>
		<span style="display:none" class="de">Startseite</span>
		<span style="display:none" class="es"></span>
		<span style="display:none" class="fr"></span>
		<span style="display:none" class="it"></span>
		<span style="display:none" class="ja">ホーム</span>
		<span style="display:none" class="zh-CN">主页</span>
		<span style="display:none" class="zh-TW">首頁</span>
	
	</a></li>
	<li id="sdk-link"><a href="../../../sdk/index.html">
		<span class="en">SDK</span>
	</a></li>
	<li id="guide-link"><a href="../../../guide/index.html" onClick="return loadLast('guide')">
	
		<span class="en">Dev Guide</span>
		<span style="display:none" class="de">Handbuch</span>
		<span style="display:none" class="es">Guía</span>
		<span style="display:none" class="fr">Guide</span>
		<span style="display:none" class="it">Guida</span>
		<span style="display:none" class="ja">開発ガイド</span>
		<span style="display:none" class="zh-CN">开发人员指南</span>
		<span style="display:none" class="zh-TW">開發指南</span>
	
	</a></li>
	<li id="reference-link"><a href="../../../reference/packages.html" onClick="return loadLast('reference')">
	
		<span class="en">Reference</span>
		<span style="display:none" class="de">Referenz</span>
		<span style="display:none" class="es">Referencia</span>
		<span style="display:none" class="fr">Référence</span>
		<span style="display:none" class="it">Riferimento</span>
		<span style="display:none" class="ja">リファレンス</span>
		<span style="display:none" class="zh-CN">参考</span>
		<span style="display:none" class="zh-TW">參考資料</span>
	
	</a></li>
	<li id="resources-link"><a href="../../../resources/index.html" onClick="return loadLast('resources')">
	
		<span class="en">Resources</span>
		<span style="display:none" class="de"></span>
		<span style="display:none" class="es"></span>
		<span style="display:none" class="fr"></span>
		<span style="display:none" class="it"></span>
    		<span style="display:none" class="ja"></span>
		<span style="display:none" class="zh-CN"></span>
		<span style="display:none" class="zh-TW"></span>
	
	</a></li>
	<li id="videos-link"><a href="../../../videos/index.html" onClick="return loadLast('videos')">
	
		<span class="en">Videos</span>
		<span style="display:none" class="de"></span>
		<span style="display:none" class="es"></span>
		<span style="display:none" class="fr"></span>
		<span style="display:none" class="it"></span>
		<span style="display:none" class="ja">ビデオ</span>
		<span style="display:none" class="zh-CN"></span>
		<span style="display:none" class="zh-TW"></span>
	
	</a></li>
	<li><a href="http://android-developers.blogspot.com" onClick="return requestAppendHL(this.href)">
	
		<span class="en">Blog</span>
		<span style="display:none" class="de"></span>
		<span style="display:none" class="es"></span>
		<span style="display:none" class="fr"></span>
		<span style="display:none" class="it"></span>
		<span style="display:none" class="ja">ブログ</span>
		<span style="display:none" class="zh-CN">博客</span>
		<span style="display:none" class="zh-TW">網誌</span>
	
	</a></li>


     
</ul>
     
      </div>
      <div id="headerRight">
          <div id="headerLinks">
          
          <a href="http://www.android.com">Android.com</a>
          </div>
  <div id="search" >
      <div id="searchForm">
          <form accept-charset="utf-8" class="gsc-search-box" 
                onsubmit="return submit_search()">
            <table class="gsc-search-box" cellpadding="0" cellspacing="0"><tbody>
                <tr>
                  <td class="gsc-input">
                    <input id="search_autocomplete" class="gsc-input" type="text" size="33" autocomplete="off"
                      title="search developer docs" name="q"
                      value="search developer docs"
                      onFocus="search_focus_changed(this, true)"
                      onBlur="search_focus_changed(this, false)"
                      onkeydown="return search_changed(event, true, '../../../')"
                      onkeyup="return search_changed(event, false, '../../../')" />
                  <div id="search_filtered_div" class="no-display">
                      <table id="search_filtered" cellspacing=0>
                      </table>
                  </div>
                  </td>
                  <td class="gsc-search-button">
                    <input type="submit" value="Search" title="search" id="search-button" class="gsc-search-button" />
                  </td>
                  <td class="gsc-clear-button">
                    <div title="clear results" class="gsc-clear-button">&nbsp;</div>
                  </td>
                </tr></tbody>
              </table>
          </form>
      </div><!-- searchForm -->
  </div><!-- search -->
      </div><!-- headerRight -->
      <script type="text/javascript">
        <!--  
        changeTabLang(getLangPref());
        //-->
      </script>
  </div><!-- header -->

  <div class="g-section g-tpl-240" id="body-content">
    <div class="g-unit g-first" id="side-nav">
      <div id="devdoc-nav">
<ul>

  <li>
    <h2><span class="en">Android Basics</span>
        <span class="de" style="display:none">Einführung in Android</span>
        <span class="es" style="display:none">Información básica sobre Android</span>
        <span class="fr" style="display:none">Présentation d'Android</span>
        <span class="it" style="display:none">Nozioni di base su Android</span>
        <span class="ja" style="display:none">Android の基本</span>
        <span class="zh-CN" style="display:none">Android 基础知识</span>
        <span class="zh-TW" style="display:none">Android 簡介</span>
    </h2>
    <ul>
      <li><a href="../../../guide/basics/what-is-android.html">
        <span class="en">What Is Android?</span>
        <span class="de" style="display:none">Was ist Android?</span>
        <span class="es" style="display:none">¿Qué es Android?</span>
        <span class="fr" style="display:none">Qu'est-ce qu'Android&nbsp;?</span>
        <span class="it" style="display:none">Che cos'è Android?</span>
        <span class="ja" style="display:none">Android とは</span>
        <span class="zh-CN" style="display:none">Android 是什么？</span>
        <span class="zh-TW" style="display:none">什麼是 Android？</span>
          </a></li>
      <li><a href="../../../guide/topics/fundamentals.html">
        <span class="en">Application Fundamentals</span>
        <span class="de" style="display:none">Anwendungsgrundlagen</span>
        <span class="es" style="display:none">Fundamentos de las aplicaciones</span>
        <span class="fr" style="display:none">Principes de base des applications</span>
        <span class="it" style="display:none">Concetti fondamentali sulle applicazioni</span>
        <span class="ja" style="display:none">開発の基礎</span>
        <span class="zh-CN" style="display:none">应用程序基础</span>
        <span class="zh-TW" style="display:none">應用程式基本原理</span>
      </a></li>

  <!--  <li><a style="color:gray;">The Android SDK</a></li> -->
  <!--  <li><a style="color:gray;">Walkthrough for Developers</a></li> -->
      <!-- quick overview of what it's like to develop on Android -->
    </ul>
  </li>

  <li>
    <h2>
      <span class="en">Framework Topics</span>
      <span class="de" style="display:none">Framework-Themen</span>
      <span class="es" style="display:none">Temas sobre el framework</span>
      <span class="fr" style="display:none">Thèmes relatifs au framework</span>
      <span class="it" style="display:none">Argomenti relativi al framework</span>
      <span class="ja" style="display:none">フレームワーク トピック</span>
      <span class="zh-CN" style="display:none">框架主题</span>
      <span class="zh-TW" style="display:none">架構主題</span>
    </h2>
    <ul>
      <li class="toggle-list">
        <div><a href="../../../guide/topics/fundamentals/activities.html">
          <span class="en">Activities</span>
        </a></div>
        <ul>
          <li><a href="../../../guide/topics/fundamentals/fragments.html">
            <span class="en">Fragments</span>
          </a></li>
          <li><a href="../../../guide/topics/fundamentals/loaders.html">
            <span class="en">Loaders</span>
          </a></li>
          <li><a href="../../../guide/topics/fundamentals/tasks-and-back-stack.html">
            <span class="en">Tasks and Back Stack</span></a></li>
        </ul>
      </li>
      <li class="toggle-list">
        <div><a href="../../../guide/topics/fundamentals/services.html">
          <span class="en">Services</span>
        </a></div>
        <ul>
          <li><a href="../../../guide/topics/fundamentals/bound-services.html">
            <span class="en">Bound Services</span>
          </a></li>
        </ul>
      </li>
      <li><a href="../../../guide/topics/providers/content-providers.html">
            <span class="en">Content Providers</span>
          </a></li>
      <li><a href="../../../guide/topics/intents/intents-filters.html">
            <span class="en">Intents and Intent Filters</span>
          </a></li>
      <li><a href="../../../guide/topics/fundamentals/processes-and-threads.html">
            <span class="en">Processes and Threads</span>
          </a></li>
    </ul>


    <ul>
      <li class="toggle-list">
        <div><a href="../../../guide/topics/ui/index.html">
            <span class="en">User Interface</span>
          </a></div>
        <ul>
          <li><a href="../../../guide/topics/ui/declaring-layout.html">
               <span class="en">XML Layouts</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/ui-events.html">
                <span class="en">Input Events</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/menus.html">
               <span class="en">Menus</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/actionbar.html">
               <span class="en">Action Bar</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/dialogs.html">
                <span class="en">Dialogs</span>
              </a></li>
          <li class="toggle-list">
            <div><a href="../../../guide/topics/ui/notifiers/index.html">
                <span class="en">Notifications</span>
            </a></div>
            <ul>
              <li><a href="../../../guide/topics/ui/notifiers/toasts.html">
                <span class="en">Toast Notifications</span>
              </a></li>
              <li><a href="../../../guide/topics/ui/notifiers/notifications.html">
                <span class="en">Status Bar Notifications</span>
              </a></li>
            </ul>
          </li>
          <li><a href="../../../guide/topics/ui/drag-drop.html">
                <span class="en">Drag and Drop</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/themes.html">
                <span class="en">Styles and Themes</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/custom-components.html">
                <span class="en">Custom Components</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/binding.html">
                <span class="en">Binding to Data with AdapterView</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/layout-objects.html">
                <span class="en">Common Layout Objects</span>
              </a></li>
          <li><a href="../../../guide/topics/ui/how-android-draws.html">
                <span class="en">How Android Draws Views</span>
              </a></li>
        </ul>
      </li><!-- end of User Interface -->

      <li class="toggle-list">
        <div><a href="../../../guide/topics/resources/index.html">
               <span class="en">Application Resources</span>
             </a></div>
        <ul>
          <li><a href="../../../guide/topics/resources/providing-resources.html">
                <span class="en">Providing Resources</span>
              </a></li>
          <li><a href="../../../guide/topics/resources/accessing-resources.html">
                <span class="en">Accessing Resources</span>
              </a></li>
          <li><a href="../../../guide/topics/resources/runtime-changes.html">
                <span class="en">Handling Runtime Changes</span>
              </a></li>
          <li><a href="../../../guide/topics/resources/localization.html">
                <span class="en">Localization</span>
              </a></li>
          <li class="toggle-list">
            <div><a href="../../../guide/topics/resources/available-resources.html">
              <span class="en">Resource Types</span>
            </a></div>
            <ul>
              <li><a href="../../../guide/topics/resources/animation-resource.html">Animation</a></li>
              <li><a href="../../../guide/topics/resources/color-list-resource.html">Color State List</a></li>
              <li><a href="../../../guide/topics/resources/drawable-resource.html">Drawable</a></li>
              <li><a href="../../../guide/topics/resources/layout-resource.html">Layout</a></li>
              <li><a href="../../../guide/topics/resources/menu-resource.html">Menu</a></li>
              <li><a href="../../../guide/topics/resources/string-resource.html">String</a></li>
              <li><a href="../../../guide/topics/resources/style-resource.html">Style</a></li>
              <li><a href="../../../guide/topics/resources/more-resources.html">More Types</a></li>
            </ul>
          </li><!-- end of resource types -->
        </ul>
      </li><!-- end of app resources -->
      <li class="toggle-list">
        <div><a href="../../../guide/topics/data/data-storage.html">
            <span class="en">Data Storage</span>
          </a></div>
          <ul>
            <li><a href="../../../guide/topics/data/backup.html">
                <span class="en">Data Backup</span>
              </a>
            </li>
          </ul>
      </li>
      <li><a href="../../../guide/topics/security/security.html">
            <span class="en">Security and Permissions</span>
          </a></li>
      <li class="toggle-list">
        <div><a href="../../../guide/topics/manifest/manifest-intro.html">
          <span class="en">The AndroidManifest.xml File</span>
        </a></div>
        <ul>
          <li><a href="../../../guide/topics/manifest/action-element.html">&lt;action&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/activity-alias-element.html">&lt;activity-alias&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/application-element.html">&lt;application&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/category-element.html">&lt;category&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/compatible-screens-element.html">&lt;compatible-screens&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/data-element.html">&lt;data&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/grant-uri-permission-element.html">&lt;grant-uri-permission&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/instrumentation-element.html">&lt;instrumentation&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/intent-filter-element.html">&lt;intent-filter&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/manifest-element.html">&lt;manifest&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/meta-data-element.html">&lt;meta-data&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/path-permission-element.html">&lt;path-permission&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/permission-element.html">&lt;permission&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/permission-group-element.html">&lt;permission-group&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/permission-tree-element.html">&lt;permission-tree&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/provider-element.html">&lt;provider&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/receiver-element.html">&lt;receiver&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/service-element.html">&lt;service&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/supports-gl-texture-element.html">&lt;supports-gl-texture&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/supports-screens-element.html">&lt;supports-screens&gt;</a></li><!-- ##api level 4## -->
          <li><a href="../../../guide/topics/manifest/uses-configuration-element.html">&lt;uses-configuration&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/uses-feature-element.html">&lt;uses-feature&gt;</a></li> <!-- ##api level 4## -->
          <li><a href="../../../guide/topics/manifest/uses-library-element.html">&lt;uses-library&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></li>
          <li><a href="../../../guide/topics/manifest/uses-sdk-element.html">&lt;uses-sdk&gt;</a></li>
        </ul>
      </li><!-- end of the manifest file -->
    </ul>

    <ul>
    <li class="toggle-list">
        <div><a href="../../../guide/topics/graphics/index.html">
            <span class="en">Graphics</span>
          </a><span class="new-child">new!</span></div>
        <ul>
          <li><a href="../../../guide/topics/graphics/2d-graphics.html">
              <span class="en">Canvas and Drawables</span></a></li>
          <li><a href="../../../guide/topics/graphics/hardware-accel.html">
              <span class="en">Hardware Acceleration</span></a>
            <span class="new">new!</span></li>
          <li><a href="../../../guide/topics/graphics/opengl.html">
              <span class="en">OpenGL</span>
            </a><span class="new">updated</span></li>
        </ul>
      </li>
      <li class="toggle-list">
        <div><a href="../../../guide/topics/graphics/animation.html">
            <span class="en">Animation</span>
          </a></div>
        <ul>
          <li><a href="../../../guide/topics/graphics/prop-animation.html">
              <span class="en">Property Animation</span></a></li>
          <li><a href="../../../guide/topics/graphics/view-animation.html">
              <span class="en">View Animation</span></a></li>
          <li><a href="../../../guide/topics/graphics/drawable-animation.html">
              <span class="en">Drawable Animation</span></a></li>
        </ul>
      </li>
      <li class="toggle-list">
	        <div><a href="../../../guide/topics/renderscript/index.html">
	            <span class="en">RenderScript</span>
	          </a></div>
	        <ul>
	          <li><a href="../../../guide/topics/renderscript/graphics.html">
	                <span class="en">Graphics</span>
	              </a>
	          </li>
	          <li><a href="../../../guide/topics/renderscript/compute.html">
	                <span class="en">Compute</span>
	              </a>
	          </li>
	        </ul>
  	  </li>

      <li class="toggle-list">
          <div><a href="../../../guide/topics/media/index.html">
            <span class="en">Multimedia and Camera</span>
          </a><span class="new">updated</span></div>
          <ul>
            <li><a href="../../../guide/topics/media/mediaplayer.html">
                  <span class="en">Media Playback</span></a>
                </li>
            <li><a href="../../../guide/topics/media/jetplayer.html">
                  <span class="en">JetPlayer</span></a>
                </li>
            <li><a href="../../../guide/topics/media/camera.html">
                  <span class="en">Camera</span></a>
                  <span class="new">new!</span>
                </li>
            <li><a href="../../../guide/topics/media/audio-capture.html">
                  <span class="en">Audio Capture</span></a>
                </li>
          </ul>
      </li>
      <li>
        <a href="../../../guide/topics/clipboard/copy-paste.html">
            <span class="en">Copy and Paste</span>
        </a></li>
  <!--<li class="toggle-list">
        <div><a style="color:gray;">Sensors</a></div>
          <ul>
            <li><a style="color:gray;">Camera</a></li>
            <li><a style="color:gray;">Compass</a></li>
            <li><a style="color:gray;">Accelerometer</a></li>
          </ul>
      </li> -->
      <li class="toggle-list">
        <div><a href="../../../guide/topics/location/index.html">
               <span class="en">Location and Maps</span>
             </a></div>
        <ul>
          <li><a href="../../../guide/topics/location/obtaining-user-location.html">
                <span class="en">Obtaining User Location</span>
              </a></li>
        </ul>
      </li>
  <!--<li class="toggle-list">
        <div><a style="color:gray;">Wireless Controls</a></div>
          <ul>
            <li><a style="color:gray;">Wi-Fi</a></li>
          </ul>
      </li> -->
  <!--<li><a style="color:gray;">Localization</a></li>  -->
      <li><a href="../../../guide/topics/appwidgets/index.html">
            <span class="en">App Widgets</span></a>
          </li>
      <li><a href="../../../guide/topics/wireless/bluetooth.html">
            <span class="en">Bluetooth</span></a>
          </li>
      <li><a href="../../../guide/topics/nfc/index.html">
            <span class="en">Near Field Communication</span>
          </a></li>
      <li class="toggle-list">
          <div><a href="../../../guide/topics/usb/index.html">
            <span class="en">USB</span></a>
          </div>
            <ul>
              <li><a href="../../../guide/topics/usb/accessory.html">Accessory</a></li>
              <li><a href="../../../guide/topics/usb/host.html">Host</a></li>
              <li><a href="../../../guide/topics/usb/adk.html">Open Accessory Dev Kit</a></li>
            </ul>
          </li>

       <li><a href="../../../guide/topics/network/sip.html">
            <span class="en">Session Initiation Protocol</span>
          </a></li>
      <li class="toggle-list">
        <div><a href="../../../guide/topics/search/index.html">
            <span class="en">Search</span>
          </a></div>
          <ul>
            <li><a href="../../../guide/topics/search/search-dialog.html">Creating a Search Interface</a></li>
            <li><a href="../../../guide/topics/search/adding-recent-query-suggestions.html">Adding Recent Query Suggestions</a></li>
            <li><a href="../../../guide/topics/search/adding-custom-suggestions.html">Adding Custom Suggestions</a></li>
            <li><a href="../../../guide/topics/search/searchable-config.html">Searchable Configuration</a></li>
          </ul>
      </li>
      <li><a href="../../../guide/topics/admin/device-admin.html">
            <span class="en">Device Administration</span></a>
      </li>
      <li class="toggle-list">
           <div>
                <a href="../../../guide/topics/testing/index.html">
                   <span class="en">Testing</span>
               </a>
           </div>
           <ul>
              <li>
                <a href="../../../guide/topics/testing/testing_android.html">
                <span class="en">Testing Fundamentals</span></a>
              </li>
              <li>
                <a href="../../../guide/topics/testing/activity_testing.html">
                <span class="en">Activity Testing</span></a>
              </li>
              <li>
                <a href="../../../guide/topics/testing/contentprovider_testing.html">
                <span class="en">Content Provider Testing</span></a>
              </li>
              <li>
                <a href="../../../guide/topics/testing/service_testing.html">
                <span class="en">Service Testing</span></a>
              </li>
              <li>
                <a href="../../../guide/topics/testing/what_to_test.html">
                <span class="en">What To Test</span></a>
              </li>
           </ul>
      </li>
    </ul>
  </li>

  <li>
    <h2>
      <span class="en">Android Market Topics</span>
    </h2>
    <ul>
      <li><a href="../../../guide/publishing/licensing.html">
          <span class="en">Application Licensing</span></a>
      </li>
      <li class="toggle-list">
        <div><a href="../../../guide/market/billing/index.html">
            <span class="en">In-app Billing</span></a>
        </div>
        <ul>
          <li><a href="../../../guide/market/billing/billing_overview.html">
              <span class="en">In-app Billing Overview</span></a>
          </li>
          <li><a href="../../../guide/market/billing/billing_integrate.html">
              <span class="en">Implementing In-app Billing</span></a>
          </li>
          <li><a href="../../../guide/market/billing/billing_best_practices.html">
              <span class="en">Security and Design</span></a>
          </li>
          <li><a href="../../../guide/market/billing/billing_testing.html">
              <span class="en">Testing In-app Billing</span></a>
          </li>
          <li><a href="../../../guide/market/billing/billing_admin.html">
              <span class="en">Administering In-app Billing</span></a>
          </li>
          <li><a href="../../../guide/market/billing/billing_reference.html">
              <span class="en">In-app Billing Reference</span></a>
          </li>
        </ul>
      </li>
      <li><a href="../../../guide/appendix/market-filters.html">
          <span class="en">Market Filters</span></a>
      </li>
      <li><a href="../../../guide/market/publishing/multiple-apks.html">
          <span class="en">Multiple APK Support</span></a>
      </li>
    </ul>
  </li>


  <li>
    <h2><span class="en">Developing</span>
               <span class="de" style="display:none">Entwicklung</span>
               <span class="es" style="display:none">Desarrollo</span>
               <span class="fr" style="display:none">Développement</span>
               <span class="it" style="display:none">Sviluppo</span>
               <span class="ja" style="display:none">開発</span>
               <span class="zh-CN" style="display:none">开发</span>
               <span class="zh-TW" style="display:none">開發</span>
    </h2>
    <ul>
  <!--<li><a href="">Developing for Android</a></li>
      signing, upgrading, selecting a package name, select device profile, touch, trackball, dpad available, etc. -->
      <li>
        <a href="../../../guide/developing/index.html">
        <span class="en">Introduction</span></a>
      </li>

      <li class="toggle-list">
        <div>
           <a href="../../../guide/developing/devices/index.html">
                <span class="en">Managing Virtual Devices</span>
            </a>
        </div>
        <ul>
          <li>
            <a href="../../../guide/developing/devices/managing-avds.html">
              <span class="en">With AVD Manager</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/devices/managing-avds-cmdline.html">
              <span class="en">From the Command Line</span>
            </a>
          </li>
          <li>
           <a href="../../../guide/developing/devices/emulator.html">
                <span class="en">Using the Android Emulator</span>
            </a>
          </li>
        </ul>
      </li>
      <li>
        <a href="../../../guide/developing/device.html">
          <span class="en">Using Hardware Devices</span>
        </a>
      </li>

      <li class="toggle-list">
        <div>
          <a href="../../../guide/developing/projects/index.html">
            <span class="en">Managing Projects</span>
          </a>
        </div>
        <ul>
          <li>
            <a href="../../../guide/developing/projects/projects-eclipse.html">
              <span class="en">From Eclipse with ADT</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/projects/projects-cmdline.html">
                <span class="en">From the Command Line</span>
            </a>
          </li>
        </ul>
      </li>

      <li class="toggle-list">
        <div>
          <a href="../../../guide/developing/building/index.html">
            <span class="en">Building and Running</span>
          </a>
        </div>
        <ul>
          <li><a href="../../../guide/developing/building/building-eclipse.html">
            <span class="en">From Eclipse with ADT</span>
          </a></li>
          <li><a href="../../../guide/developing/building/building-cmdline.html">
            <span class="en">From the Command Line</span></a></li>
        </ul>
      </li>

      <li class="toggle-list">
        <div>
          <a href="../../../guide/developing/debugging/index.html">
            <span class="en">Debugging</span>
          </a>
        </div>
        <ul>
          <li>
            <a href="../../../guide/developing/debugging/debugging-projects.html">
                <span class="en">From Eclipse with ADT</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/debugging/debugging-projects-cmdline.html">
                <span class="en">From Other IDEs</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/debugging/ddms.html">
              <span class="en">Using DDMS</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/debugging/debugging-log.html">
                <span class="en">Reading and Writing Logs</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/debugging/debugging-ui.html">
                <span class="en">Debugging and Profiling UIs</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/debugging/debugging-tracing.html">
                <span class="en">Profiling with Traceview and dmtracedump</span>
            </a>
          </li>
          <li>
            <a href="../../../guide/developing/debugging/debugging-devtools.html">
                <span class="en">Using the Dev Tools App</span>
            </a>
          </li>
        </ul>
      </li>

      <li class="toggle-list">
           <div>
                <a href="../../../guide/developing/testing/index.html">
                   <span class="en">Testing</span>
               </a>
           </div>
           <ul>
              <li>
                <a href="../../../guide/developing/testing/testing_eclipse.html">
                  <span class="en">From Eclipse with ADT</span>
                </a>
              </li>

              <li>
                <a href="../../../guide/developing/testing/testing_otheride.html">
                  <span class="en">From Other IDEs</span>
                </a>
              </li>
           </ul>
         </li>

         <li class="toggle-list">
        <div><a href="../../../guide/developing/tools/index.html">
            <span class="en">Tools</span>
          </a></div>
        <ul>
          <li><a href="../../../guide/developing/tools/adb.html">adb</a></li>
          <li><a href="../../../guide/developing/tools/adt.html">ADT</a></li>
          <li><a href="../../../guide/developing/tools/android.html">android</a></li>
          <li><a href="../../../guide/developing/tools/bmgr.html">bmgr</a>
          <li><a href="../../../guide/developing/tools/dmtracedump.html">dmtracedump</a></li>
          <li><a href="../../../guide/developing/tools/draw9patch.html">Draw
          9-Patch</a></li>
          <li><a href="../../../guide/developing/tools/emulator.html">Emulator</a></li>
          <li><a href="../../../guide/developing/tools/etc1tool.html">etc1tool</a></li>
          <li><a href="../../../guide/developing/tools/hierarchy-viewer.html">Hierarchy Viewer</a></li>
          <li><a href="../../../guide/developing/tools/hprof-conv.html">hprof-conv</a></li>
          <li><a href="../../../guide/developing/tools/layoutopt.html">layoutopt</a></li>
          <li><a href="../../../guide/developing/tools/logcat.html">logcat</a></li>
          <li><a href="../../../guide/developing/tools/mksdcard.html">mksdcard</a></li>
          <li><a href="../../../guide/developing/tools/monkey.html">Monkey</a></li>
          <li class="toggle-list">
            <div><a href="../../../guide/developing/tools/monkeyrunner_concepts.html">
              <span class="en">monkeyrunner</span>
            </a></div>
            <ul>
              <li><a href="../../../guide/developing/tools/MonkeyDevice.html">
                <span class="en">MonkeyDevice</span>
                </a></li>
              <li><a href="../../../guide/developing/tools/MonkeyImage.html">
                <span class="en">MonkeyImage</span>
                </a></li>
              <li><a href="../../../guide/developing/tools/MonkeyRunner.html">
                <span class="en">MonkeyRunner</span>
                </a></li>
            </ul>
          </li>
          <li><a href="../../../guide/developing/tools/proguard.html">ProGuard</a></li>
          <li><a href="../../../guide/developing/tools/adb.html#sqlite">sqlite3</a></li>
          <li><a href="../../../guide/developing/tools/traceview.html">Traceview</a></li>
          <li><a href="../../../guide/developing/tools/zipalign.html">zipalign</a></li>
        </ul>
      </li>
    </ul>
  </li>

  <li>
    <h2><span class="en">Publishing</span>
        <span class="de" style="display:none">Veröffentlichung</span>
        <span class="es" style="display:none">Publicación</span>
        <span class="fr" style="display:none">Publication</span>
        <span class="it" style="display:none">Pubblicazione</span>
        <span class="ja" style="display:none">公開</span>
        <span class="zh-CN" style="display:none">发布</span>
        <span class="zh-TW" style="display:none">發佈</span>
    </h2>
    <ul>
      <li><a href="../../../guide/publishing/app-signing.html">
            <span class="en">Signing Your Applications</span>
            <span class="de" style="display:none">Signieren Ihrer Anwendungen</span>
            <span class="es" style="display:none">Firma de aplicaciones</span>
            <span class="fr" style="display:none">Attribution de votre signature <br />à vos applications</span>
            <span class="it" style="display:none">Firma delle applicazioni</span>
            <span class="ja" style="display:none">アプリケーションへの署名</span>
            <span class="zh-CN" style="display:none">应用程序签名</span>
            <span class="zh-TW" style="display:none">簽署應用程式</span>
          </a></li>
      <li><a href="../../../guide/publishing/versioning.html">
            <span class="en">Versioning Your Applications</span>
            <span class="de" style="display:none">Versionsverwaltung für Ihre <br />Anwendungen</span>
            <span class="es" style="display:none">Versiones de las aplicaciones</span>
            <span class="fr" style="display:none">Attribution d'une version à vos applications</span>
            <span class="it" style="display:none">Controllo versioni delle applicazioni</span>
            <span class="ja" style="display:none">アプリケーションのバージョニング</span>
            <span class="zh-CN" style="display:none">应用程序版本控制</span>
            <span class="zh-TW" style="display:none">應用程式版本設定</span>
          </a></li>
      <li><a href="../../../guide/publishing/preparing.html">
            <span class="en">Preparing to Publish</span>
            <span class="de" style="display:none">Vorbereitung auf die Veröffentlichung</span>
            <span class="es" style="display:none">Publicación de aplicaciones</span>
            <span class="fr" style="display:none">Préparation à la publication</span>
            <span class="it" style="display:none">Preparativi per la pubblicazione</span>
            <span class="ja" style="display:none">公開の準備</span>
            <span class="zh-CN" style="display:none">准备发布</span>
            <span class="zh-TW" style="display:none">準備發佈</span>
          </a></li>
      <li><a href="../../../guide/publishing/publishing.html">
            <span class="en">Publishing on Android Market</span>
          </a></li>
    </ul>
  </li>

  <li>
    <h2><span class="en">Best Practices</span>
               <span class="de" style="display:none">Bewährte Verfahren</span>
               <span class="es" style="display:none">Prácticas recomendadas</span>
               <span class="fr" style="display:none">Meilleures pratiques</span>
               <span class="it" style="display:none">Best practice</span>
               <span class="ja" style="display:none">ベスト プラクティス</span>
               <span class="zh-CN" style="display:none">最佳实践</span>
               <span class="zh-TW" style="display:none">最佳實務</span>
    </h2>
    <ul>
      <li><a href="../../../guide/practices/compatibility.html">
            <span class="en">Compatibility</span>
          </a></li>
      <li class="toggle-list">
        <div><a href="../../../guide/practices/screens_support.html">
          <span class="en">Supporting Multiple Screens</span>
        </a></div>
        <ul>
          <li><a href="../../../guide/practices/screens-distribution.html">
            <span class="en">Distributing to Specific Screens</span>
          </a></li>
          <li><a href="../../../guide/practices/screen-compat-mode.html">
            <span class="en">Screen Compatibility Mode</span>
          </a></li>
          <li><a href="../../../guide/practices/screens-support-1.5.html">
            <span class="en">Strategies for Android 1.5</span>
          </a></li>
        </ul>
      </li>
      <li><a href="../../../guide/practices/optimizing-for-3.0.html">
            <span class="en">Optimizing Apps for Android 3.0</span>
          </a></li>
      <li class="toggle-list">
        <div><a href="../../../guide/practices/ui_guidelines/index.html">
               <span class="en">UI Guidelines</span>
             </a></div>
        <ul>
          <li class="toggle-list">
            <div><a href="../../../guide/practices/ui_guidelines/icon_design.html">
                   <span class="en">Icon Design <span class="new">updated</span></span>
                 </a></div>
            <ul>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_launcher.html">
                    <span class="en">Launcher Icons <span class="new">updated</span></span>
                  </a></li>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_menu.html">
                    <span class="en">Menu Icons</span>
                  </a></li>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_action_bar.html">
                    <span class="en">Action Bar Icons <span class="new">new!</span></span>
                  </a></li>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_status_bar.html">
                    <span class="en">Status Bar Icons <span class="new">updated</span></span>
                  </a></li>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_tab.html">
                    <span class="en">Tab Icons</span>
                  </a></li>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_dialog.html">
                    <span class="en">Dialog Icons</span>
                  </a></li>
              <li><a href="../../../guide/practices/ui_guidelines/icon_design_list.html">
                    <span class="en">List View Icons</span>
                  </a></li>
            </ul>
          </li>
          <li><a href="../../../guide/practices/ui_guidelines/widget_design.html">
                <span class="en">App Widget Design <span class="new">updated</span></span>
              </a></li>
          <li><a href="../../../guide/practices/ui_guidelines/activity_task_design.html">
                <span class="en">Activity and Task Design</span>
              </a></li>
          <li><a href="../../../guide/practices/ui_guidelines/menu_design.html">
                <span class="en">Menu Design</span>
              </a></li>
        </ul>
      </li>
      </ul>
      <ul>
      <li><a href="../../../guide/practices/design/accessibility.html">
            <span class="en">Designing for Accessibility</span>
          </a></li>
      <li class="toggle-list">
        <div><a href="../../../guide/practices/design/performance.html">
            <span class="en">Designing for Performance</span>
          </a></div>
        <ul>
          <li><a href="../../../guide/practices/design/jni.html">
                <span class="en">JNI Tips</span>
              </a></li>
        </ul>
      </li>
      <li><a href="../../../guide/practices/design/responsiveness.html">
            <span class="en">Designing for Responsiveness</span>
          </a></li>
      <li><a href="../../../guide/practices/design/seamlessness.html">
            <span class="en">Designing for Seamlessness</span>
          </a></li>
    </ul>
  </li>

  <li>
    <h2><span class="en">Web Applications</span>
    </h2>
    <ul>
      <li><a href="../../../guide/webapps/index.html">
            <span class="en">Web Apps Overview</span>
          </a></li>
      <li><a href="../../../guide/webapps/targeting.html">
            <span class="en">Targeting Screens from Web Apps</span>
          </a></li>
      <li><a href="../../../guide/webapps/webview.html">
            <span class="en">Building Web Apps in WebView</span>
          </a></li>
      <li><a href="../../../guide/webapps/debugging.html">
            <span class="en">Debugging Web Apps</span>
          </a></li>
      <li><a href="../../../guide/webapps/best-practices.html">
            <span class="en">Best Practices for Web Apps</span>
          </a></li>
    </ul>
  </li>

  <li>
    <h2><span class="en">Appendix</span>
               <span class="de" style="display:none">Anhang</span>
               <span class="es" style="display:none">Apéndice</span>
               <span class="fr" style="display:none">Annexes</span>
               <span class="it" style="display:none">Appendice</span>
               <span class="ja" style="display:none">付録</span>
               <span class="zh-CN" style="display:none">附录</span>
               <span class="zh-TW" style="display:none">附錄</span>
    </h2>
    <ul>
      <li><a href="../../../guide/appendix/api-levels.html">
            <span class="en">Android API Levels</span>
          </a></li>
      <li><a href="../../../guide/appendix/install-location.html">
            <span class="en">App Install Location</span>
          </a></li>
      <li><a href="../../../guide/appendix/media-formats.html">
            <span class="en">Supported Media Formats <span class="new">updated</span></span>
          </a></li>
      <li><a href="../../../guide/appendix/g-app-intents.html">
            <span class="en">Intents List: Google Apps</span>
          </a></li>
      <li><a href="../../../guide/developing/tools/aidl.html">AIDL</a></li>
      <li><a href="../../../guide/appendix/glossary.html">
            <span class="en">Glossary</span>
          </a></li>
    </ul>
  </li>

</ul>

<script type="text/javascript">
<!--
    buildToggleLists();
    changeNavLang(getLangPref());
//-->
</script>

      </div>
    </div> <!-- end side-nav -->
    <script>
      addLoadEvent(function() {
        scrollIntoView("devdoc-nav");
        });
    </script>




<div class="g-unit" id="doc-content"><a name="top"></a>

<div id="jd-header" class="guide-header">
  <span class="crumb">
    
      <a href="index.html">Graphics</a> >
    
  </span>
<h1>Canvas and Drawables</h1>
</div>

  <div id="jd-content">

    <div class="jd-descr">
    <div id="qv-wrapper">
  <div id="qv">
  <h2>In this document</h2>
  <ol>
    <li><a href="#draw-with-canvas">Draw with a Canvas</a>
    <ol>
      <li><a href="#on-view">On a View</a></li>
      <li><a href="#on-surfaceview">On a SurfaceView</a></li>
    </ol>
    </li>
    <li><a href="#drawables">Drawables</a>
        <ol>
          <li><a href="#drawables-from-images">Creating from resource images</a></li>
          <li><a href="#drawables-from-xml">Creating from resource XML</a></li>
        </ol>
    </li>
    <li><a href="#shape-drawable">Shape Drawable</a></li>
    <li><a href="#nine-patch">Nine-patch</a></li>
  </ol>

  <h2>See also</h2>
  <ol>
    <li><a href="../../../guide/topics/graphics/opengl.html">OpenGL with the Framework
APIs</a></li>
    <li><a href="../../../guide/topics/renderscript/index.html">RenderScript</a></li>
  </ol>
  </div>
</div>

<p>The Android framework APIs provides a set 2D drawing APIs that allow you to render your own
custom graphics onto a canvas or to modify existing Views to customize their look and feel.
When drawing 2D graphics, you'll typically do so in one of two ways:</p>

<ol type="a">
  <li>Draw your graphics or animations into a View object from your layout. In this manner,
  the drawing of your graphics is handled by the system's
  normal View hierarchy drawing process &mdash; you simply define the graphics to go inside the View.</li>
  <li>Draw your graphics directly to a Canvas. This way, you personally call the appropriate class's
  <code><a href="../../../reference/android/view/View.html#onDraw(android.graphics.Canvas)">onDraw()</a></code> method (passing it your Canvas), or one of the Canvas
<code>draw...()</code> methods (like
  <code><code><a href="../../../reference/android/graphics/Canvas.html#drawPicture(android.graphics.Picture, android.graphics.Rect)">drawPicture()</a></code></code>). In doing so, you are also in
  control of any animation.</li>
</ol>

<p>Option "a," drawing to a View, is your best choice when you want to draw simple graphics that do not
need to change dynamically and are not part of a performance-intensive game. For example, you should
draw your graphics into a View when you want to display a static graphic or predefined animation, within
an otherwise static application. Read <a href="#drawables">Drawables</a> for more information.</li>
</p>

<p>Option "b," drawing to a Canvas, is better when your application needs to regularly re-draw itself.
Applications such as video games should be drawing to the Canvas on its own. However, there's more than
one way to do this:</p>

<ul>
  <li>In the same thread as your UI Activity, wherein you create a custom View component in
  your layout, call <code><code><a href="../../../reference/android/view/View.html#invalidate()">invalidate()</a></code></code> and then handle the
  <code><code><a href="../../../reference/android/view/View.html#onDraw(android.graphics.Canvas)">onDraw()</a></code></code> callback.</li>
  <li>Or, in a separate thread, wherein you manage a <code><a href="../../../reference/android/view/SurfaceView.html">SurfaceView</a></code> and
  perform draws to the Canvas as fast as your thread is capable
  (you do not need to request <code>invalidate()</code>).</li>
</ul>

<h2 id="draw-with-canvas">Draw with a Canvas</h2>

<p>When you're writing an application in which you would like to perform specialized drawing
and/or control the animation of graphics,
you should do so by drawing through a <code><a href="../../../reference/android/graphics/Canvas.html">Canvas</a></code>. A Canvas works for you as
a pretense, or interface, to the actual surface upon which your graphics will be drawn &mdash; it
holds all of your "draw" calls. Via the Canvas, your drawing is actually performed upon an
underlying <code><a href="../../../reference/android/graphics/Bitmap.html">Bitmap</a></code>, which is placed into the window.</p>

<p>In the event that you're drawing within the <code><code><a href="../../../reference/android/view/View.html#onDraw(android.graphics.Canvas)">onDraw()</a></code></code>
callback method, the Canvas is provided for you and you need only place your drawing calls upon it.
You can also acquire a Canvas from <code><code><a href="../../../reference/android/view/SurfaceHolder.html#lockCanvas()">SurfaceHolder.lockCanvas()</a></code></code>,
when dealing with a SurfaceView object. (Both of these scenarios are discussed in the following sections.)
However, if you need to create a new Canvas, then you must define the <code><a href="../../../reference/android/graphics/Bitmap.html">Bitmap</a></code>
upon which drawing will actually be performed. The Bitmap is always required for a Canvas. You can set up
a new Canvas like this:</p>
<pre>
Bitmap b = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(b);
</pre>

<p>Now your Canvas will draw onto the defined Bitmap. After drawing upon it with the Canvas, you can then carry your
Bitmap to another Canvas with one of the <code><code><a href="../../../reference/android/graphics/Canvas.html#drawBitmap(android.graphics.Bitmap, android.graphics.Matrix, android.graphics.Paint)">Canvas.drawBitmap(Bitmap,...)</a></code></code> methods. It's recommended that you ultimately draw your final
graphics through a Canvas offered to you
by <code><code><a href="../../../reference/android/view/View.html#onDraw(android.graphics.Canvas)">View.onDraw()</a></code></code> or
<code><code><a href="../../../reference/android/view/SurfaceHolder.html#lockCanvas()">SurfaceHolder.lockCanvas()</a></code></code> (see the following sections).</p>

<p>The <code><a href="../../../reference/android/graphics/Canvas.html">Canvas</a></code> class has its own set of drawing methods that you can use,
like <code>drawBitmap(...)</code>, <code>drawRect(...)</code>, <code>drawText(...)</code>, and many more.
Other classes that you might use also have <code>draw()</code> methods. For example, you'll probably
have some <code><a href="../../../reference/android/graphics/drawable/Drawable.html">Drawable</a></code> objects that you want to put on the Canvas. Drawable
has its own <code><code><a href="../../../reference/android/graphics/drawable/Drawable.html#draw(android.graphics.Canvas)">draw()</a></code></code> method
that takes your Canvas as an argument.</p>


<h3 id="on-view">On a View</h3>

<p>If your application does not require a significant amount of processing or
frame-rate speed (perhaps for a chess game, a snake game,
or another slowly-animated application), then you should consider creating a custom View component
and drawing with a Canvas in <code><code><a href="../../../reference/android/view/View.html#onDraw(android.graphics.Canvas)">View.onDraw()</a></code></code>.
The most convenient aspect of doing so is that the Android framework will
provide you with a pre-defined Canvas to which you will place your drawing calls.</p>

<p>To start, extend the <code><a href="../../../reference/android/view/View.html">View</a></code> class (or descendant thereof) and define
the <code><code><a href="../../../reference/android/view/View.html#onDraw(android.graphics.Canvas)">onDraw()</a></code></code> callback method. This method will be called by the Android
framework to request that your View draw itself. This is where you will perform all your calls
to draw through the <code><a href="../../../reference/android/graphics/Canvas.html">Canvas</a></code>, which is passed to you through the <code>onDraw()</code> callback.</p>

<p>The Android framework will only call <code>onDraw()</code> as necessary. Each time that
your application is prepared to be drawn, you must request your View be invalidated by calling
<code><code><a href="../../../reference/android/view/View.html#invalidate()">invalidate()</a></code></code>. This indicates that you'd like your View to be drawn and
Android will then call your <code>onDraw()</code> method (though is not guaranteed that the callback will
be instantaneous). </p>

<p>Inside your View component's <code>onDraw()</code>, use the Canvas given to you for all your drawing,
using various <code>Canvas.draw...()</code> methods, or other class <code>draw()</code> methods that
take your Canvas as an argument. Once your <code>onDraw()</code> is complete, the Android framework will
use your Canvas to draw a Bitmap handled by the system.</p>

<p class="note"><strong>Note: </strong> In order to request an invalidate from a thread other than your main
Activity's thread, you must call <code><code><a href="../../../reference/android/view/View.html#postInvalidate()">postInvalidate()</a></code></code>.</p>

<p>Also read <a href="../../../guide/topics/ui/custom-components.html">Building Custom Components</a>
for a guide to extending a View class, and <a href="2d-graphics.html">2D Graphics: Drawables</a> for
information on using Drawable objects like images from your resources and other primitive shapes.</p>

<p>For a sample application, see the Snake game, in the SDK samples folder:
<code>&lt;your-sdk-directory>/samples/Snake/</code>.</p>

<h3 id="on-surfaceview">On a SurfaceView</h3>

<p>The <code><a href="../../../reference/android/view/SurfaceView.html">SurfaceView</a></code> is a special subclass of View that offers a dedicated
drawing surface within the View hierarchy. The aim is to offer this drawing surface to
an application's secondary thread, so that the application isn't required
to wait until the system's View hierarchy is ready to draw. Instead, a secondary thread
that has reference to a SurfaceView can draw to its own Canvas at its own pace.</p>

<p>To begin, you need to create a new class that extends <code><a href="../../../reference/android/view/SurfaceView.html">SurfaceView</a></code>. The class should also
implement <code><a href="../../../reference/android/view/SurfaceHolder.Callback.html">SurfaceHolder.Callback</a></code>. This subclass is an interface that will notify you
with information about the underlying <code><a href="../../../reference/android/view/Surface.html">Surface</a></code>, such as when it is created, changed, or destroyed.
These events  are important so that you know when you can start drawing, whether you need
to make adjustments based on new surface properties, and when to stop drawing and potentially
kill some tasks. Inside your SurfaceView class is also a good place to define your secondary Thread class, which will
perform all the drawing procedures to your Canvas.</p>

<p>Instead of handling the Surface object directly, you should handle it via
a <code><a href="../../../reference/android/view/SurfaceHolder.html">SurfaceHolder</a></code>. So, when your SurfaceView is initialized, get the SurfaceHolder by calling
<code><code><a href="../../../reference/android/view/SurfaceView.html#getHolder()">getHolder()</a></code></code>. You should then notify the SurfaceHolder that you'd
like to receive SurfaceHolder callbacks (from <code><a href="../../../reference/android/view/SurfaceHolder.Callback.html">SurfaceHolder.Callback</a></code>) by calling
<code><a href="../../../reference/android/view/SurfaceHolder.html#addCallback(android.view.SurfaceHolder.Callback)">addCallback()</a></code>
(pass it <var>this</var>). Then override each of the
<code><a href="../../../reference/android/view/SurfaceHolder.Callback.html">SurfaceHolder.Callback</a></code> methods inside your SurfaceView class.</p>

<p>In order to draw to the Surface Canvas from within your second thread, you must pass the thread your SurfaceHandler
and retrieve the Canvas with <code><code><a href="../../../reference/android/view/SurfaceHolder.html#lockCanvas()">lockCanvas()</a></code></code>.
You can now take the Canvas given to you by the SurfaceHolder and do your necessary drawing upon it.
Once you're done drawing with the Canvas, call
<code><code><a href="../../../reference/android/view/SurfaceHolder.html#unlockCanvasAndPost(android.graphics.Canvas)">unlockCanvasAndPost()</a></code></code>, passing it
your Canvas object. The Surface will now draw the Canvas as you left it. Perform this sequence of locking and
unlocking the canvas each time you want to redraw.</p>

<p class="note"><strong>Note:</strong> On each pass you retrieve the Canvas from the SurfaceHolder,
the previous state of the Canvas will be retained. In order to properly animate your graphics, you must re-paint the
entire surface. For example, you can clear the previous state of the Canvas by filling in a color
with <code><code><a href="../../../reference/android/graphics/Canvas.html#drawColor(int)">drawColor()</a></code></code> or setting a background image
with <code><code><a href="../../../reference/android/graphics/Canvas.html#drawBitmap(android.graphics.Bitmap, android.graphics.Rect, android.graphics.RectF, android.graphics.Paint)">drawBitmap()</a></code></code>. Otherwise,
you will see traces of the drawings you previously performed.</p>


<p>For a sample application, see the Lunar Lander game, in the SDK samples folder:
<code>&lt;your-sdk-directory>/samples/LunarLander/</code>. Or,
browse the source in the <a href="../../../guide/samples/index.html">Sample Code</a> section.</p>

<h2 id="drawables">Drawables</h2>
<p>Android offers a custom 2D graphics library for drawing shapes and images.
  The <code><a href="../../../reference/android/graphics/drawable/package-summary.html">android.graphics.drawable</a></code> package is where you'll find the common classes used for
  drawing in two-dimensions.</p>

<p>This document discusses the basics of using Drawable objects to draw graphics and how to use a
couple subclasses of the Drawable class. For information on using Drawables to do frame-by-frame
animation, see <a href="../../../guide/topics/animation/frame-animation.html">Frame-by-Frame
Animation</a>.</p>

<p>A <code><a href="../../../reference/android/graphics/drawable/Drawable.html">Drawable</a></code> is a general abstraction for "something that can be
  drawn."  You'll discover that the Drawable class extends to define a variety of specific kinds of
drawable graphics, including <code><a href="../../../reference/android/graphics/drawable/BitmapDrawable.html">BitmapDrawable</a></code>, <code><a href="../../../reference/android/graphics/drawable/ShapeDrawable.html">ShapeDrawable</a></code>, <code><a href="../../../reference/android/graphics/drawable/PictureDrawable.html">PictureDrawable</a></code>,
<code><a href="../../../reference/android/graphics/drawable/LayerDrawable.html">LayerDrawable</a></code>, and several more.  Of course, you can also extend
these to define your own custom Drawable objects that behave in unique ways.</p>

<p>There are three ways to define and instantiate a Drawable: using an image saved in your project
  resources; using an XML file that defines the Drawable properties; or using the normal class
constructors. Below, we'll discuss each the first two techniques (using constructors is nothing new
for an experienced developer).</p>


<h3 id="drawables-from-images">Creating from resource images</h3>

<p>A simple way to add graphics to your application is by referencing an image file from your
  project resources. Supported file types are PNG (preferred), JPG (acceptable) and GIF
(discouraged). This technique would obviously be preferred for application icons, logos, or other
graphics such as those used in a game.</p>

<p>To use an image resource, just add your file to the <code>res/drawable/</code> directory of your
  project. From there, you can reference it from your code or your XML layout.
  Either way, it is referred using a resource ID, which is the file name without the file type
  extension (E.g., <code>my_image.png</code> is referenced as <var>my_image</var>).</p>

<p class="note"><strong>Note:</strong> Image resources placed in <code>res/drawable/</code> may be
  automatically optimized with lossless image compression by the
  <code>aapt</code> tool during the build process. For example, a true-color PNG that does
  not require more than 256 colors may be converted to an 8-bit PNG with a color palette. This
  will result in an image of equal quality but which requires less memory. So be aware that the
  image binaries placed in this directory can change during the build. If you plan on reading
  an image as a bit stream in order to convert it to a bitmap, put your images in the
  <code>res/raw/</code> folder instead, where they will not be optimized.</p>

<h4>Example code</h4>
<p>The following code snippet demonstrates how to build an <code><a href="../../../reference/android/widget/ImageView.html">ImageView</a></code> that
  uses an image from drawable resources and add it to the layout.</p>
<pre>
  LinearLayout mLinearLayout;

  protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);

  // Create a LinearLayout in which to add the ImageView
  mLinearLayout = new LinearLayout(this);

  // Instantiate an ImageView and define its properties
  ImageView i = new ImageView(this);
  i.setImageResource(R.drawable.my_image);
  i.setAdjustViewBounds(true); // set the ImageView bounds to match the Drawable's dimensions
  i.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,
  LayoutParams.WRAP_CONTENT));

  // Add the ImageView to the layout and set the layout as the content view
  mLinearLayout.addView(i);
  setContentView(mLinearLayout);
  }
</pre>
<p>In other cases, you may want to handle your image resource as a
  <code><a href="../../../reference/android/graphics/drawable/Drawable.html">Drawable</a></code> object.
  To do so, create a Drawable from the resource like so:
  <pre>
    Resources res = mContext.getResources();
    Drawable myImage = res.getDrawable(R.drawable.my_image);
  </pre>

  <p class="warning"><strong>Note:</strong> Each unique resource in your project can maintain only
one state, no matter how many different objects you may instantiate for it. For example, if you
    instantiate two Drawable objects from the same image resource, then change a property (such
as the alpha) for one of the Drawables, then it will also affect the other. So when dealing with
multiple instances of an image resource, instead of directly transforming the Drawable, you
should perform a <a href="../../../guide/topics/graphics/view-animation.html#tween-animation">tween
animation</a>.</p>


  <h4>Example XML</h4>
  <p>The XML snippet below shows how to add a resource Drawable to an
    <code><a href="../../../reference/android/widget/ImageView.html">ImageView</a></code> in the XML layout (with some red tint just for fun).
    <pre>
      &lt;ImageView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:tint="#55ff0000"
      android:src="@drawable/my_image"/>
  </pre>
  <p>For more information on using project resources, read about
    <a href="../../../guide/topics/resources/index.html">Resources and Assets</a>.</p>


  <h3 id="drawables-from-xml">Creating from resource XML</h3>

  <p>By now, you should be familiar with Android's principles of developing a
    <a href="../../../guide/topics/ui/index.html">User Interface</a>. Hence, you understand the
power and flexibility inherent in defining objects in XML. This philosophy caries over from Views
to Drawables.  If there is a Drawable object that you'd like to create, which is not initially
dependent on variables defined by your application code or user interaction, then defining the
Drawable in XML is a good option. Even if you expect your Drawable to change its properties
during the user's experience with your application, you should consider defining the object in
XML, as you can always modify properties once it is instantiated.</p>

  <p>Once you've defined your Drawable in XML, save the file in the <code>res/drawable/</code>
    directory of your project. Then, retrieve and instantiate the object by calling
    <code><a href="../../../reference/android/content/res/Resources.html#getDrawable(int)">Resources.getDrawable()</a></code>, passing it the
    resource ID of your XML file. (See the <a href="#drawable-xml-example">example
below</a>.)</p>

  <p>Any Drawable subclass that supports the <code>inflate()</code> method can be defined in
    XML and instantiated by your application. Each Drawable that supports XML inflation utilizes
specific XML attributes that help define the object
    properties (see the class reference to see what these are). See the class documentation for each
    Drawable subclass for information on how to define it in XML.

    <h4 id="drawable-xml-example">Example</h4>
    <p>Here's some XML that defines a TransitionDrawable:</p>
    <pre>
      &lt;transition xmlns:android="http://schemas.android.com/apk/res/android">
      &lt;item android:drawable="&#64;drawable/image_expand">
      &lt;item android:drawable="&#64;drawable/image_collapse">
      &lt;/transition>
    </pre>

    <p>With this XML saved in the file <code>res/drawable/expand_collapse.xml</code>,
      the following code will instantiate the TransitionDrawable and set it as the content of an
      ImageView:</p>
    <pre>
      Resources res = mContext.getResources();
      TransitionDrawable transition = (TransitionDrawable)
res.getDrawable(R.drawable.expand_collapse);
      ImageView image = (ImageView) findViewById(R.id.toggle_image);
      image.setImageDrawable(transition);
    </pre>
    <p>Then this transition can be run forward (for 1 second) with:</p>
    <pre>transition.startTransition(1000);</pre>

    <p>Refer to the Drawable classes listed above for more information on the XML attributes
supported by each.</p>



    <h2 id="shape-drawable">Shape Drawable</h2>

    <p>When you want to dynamically draw some two-dimensional graphics, a <code><a href="../../../reference/android/graphics/drawable/ShapeDrawable.html">ShapeDrawable</a></code>
      object will probably suit your needs. With a ShapeDrawable, you can programmatically draw
      primitive shapes and style them in any way imaginable.</p>

    <p>A ShapeDrawable is an extension of <code><a href="../../../reference/android/graphics/drawable/Drawable.html">Drawable</a></code>, so you can use
one      where ever
      a Drawable is expected &mdash; perhaps for the background of a View, set with
      <code><a href="../../../reference/android/view/View.html#setBackgroundDrawable(android.graphics.drawable.Drawable)">setBackgroundDrawable()</a></code>.
      Of course, you can also draw your shape as its own custom <code><a href="../../../reference/android/view/View.html">View</a></code>,
      to be added to your layout however you please.
      Because the ShapeDrawable has its own <code>draw()</code> method, you can create a subclass of
View      that
      draws the ShapeDrawable during the <code>View.onDraw()</code> method.
      Here's a basic extension of the View class that does just this, to draw a ShapeDrawable as a
      View:</p>
    <pre>
      public class CustomDrawableView extends View {
      private ShapeDrawable mDrawable;

      public CustomDrawableView(Context context) {
      super(context);

      int x = 10;
      int y = 10;
      int width = 300;
      int height = 50;

      mDrawable = new ShapeDrawable(new OvalShape());
      mDrawable.getPaint().setColor(0xff74AC23);
      mDrawable.setBounds(x, y, x + width, y + height);
      }

      protected void onDraw(Canvas canvas) {
      mDrawable.draw(canvas);
      }
      }
    </pre>

    <p>In the constructor, a ShapeDrawable is defines as an <code><a href="../../../reference/android/graphics/drawable/shapes/OvalShape.html">OvalShape</a></code>.
      It's then given a color and the bounds of the shape are set. If you do not set the bounds,
then the
      shape will not be drawn, whereas if you don't set the color, it will default to black.</p>
    <p>With the custom View defined, it can be drawn any way you like. With the sample above, we can
      draw the shape programmatically in an Activity:</p>
    <pre>
      CustomDrawableView mCustomDrawableView;

      protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      mCustomDrawableView = new CustomDrawableView(this);

      setContentView(mCustomDrawableView);
      }
    </pre>

    <p>If you'd like to draw this custom drawable from the XML layout instead of from the Activity,
      then the CustomDrawable class must override the <code><a href="../../../reference/android/view/View.html#View(android.content.Context, android.util.AttributeSet)">View(Context,
      AttributeSet)</a></code> constructor, which is called when
      instantiating a View via inflation from XML. Then add a CustomDrawable element to the XML,
      like so:</p>
    <pre>
      &lt;com.example.shapedrawable.CustomDrawableView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      />
  </pre>

  <p>The ShapeDrawable class (like many other Drawable types in the <code><a href="../../../reference/android/graphics/drawable/package-summary.html">android.graphics.drawable</a></code>    package)
    allows you to define various properties of the drawable with public methods.
    Some properties you might want to adjust include
    alpha transparency, color filter, dither, opacity and color.</p>

  <p>You can also define primitive drawable shapes using XML. For more information, see the
    section about Shape Drawables in the <a

href="../../../guide/topics/resources/drawable-resource.html#Shape">Drawable Resources</a>
    document.</p>

  <!-- TODO
       <h2 id="state-list">StateListDrawable</h2>

       <p>A StateListDrawable is an extension of the DrawableContainer class, making it  little
different.
         The primary distinction is that the
         StateListDrawable manages a collection of images for the Drawable, instead of just one.
         This means that it can switch the image when you want, without switching objects. However,
the
         intention of the StateListDrawable is to automatically change the image used based on the
state
         of the object it's attached to.
         -->

         <h2 id="nine-patch">Nine-patch</h2>

         <p>A <code><a href="../../../reference/android/graphics/drawable/NinePatchDrawable.html">NinePatchDrawable</a></code> graphic is a stretchable bitmap
image,           which Android
           will automatically resize to accommodate the contents of the View in which you have
placed it as the           background.
           An example use of a NinePatch is the backgrounds used by standard Android buttons &mdash;
           buttons must stretch to accommodate strings of various lengths. A NinePatch drawable is a
standard           PNG
           image that includes an extra 1-pixel-wide border. It must be saved with the extension
           <code>.9.png</code>,
           and saved into the <code>res/drawable/</code> directory of your project.
         </p>
         <p>
           The border is used to define the stretchable and static areas of
           the image. You indicate a stretchable section by drawing one (or more) 1-pixel-wide
           black line(s) in the left and top part of the border (the other border pixels should
           be fully transparent or white). You can have as many stretchable sections as you want:
           their relative size stays the same, so the largest sections always remain the largest.
         </p>
         <p>
           You can also define an optional drawable section of the image (effectively,
           the padding lines) by drawing a line on the right and bottom lines.
           If a View object sets the NinePatch as its background and then specifies the
           View's text, it will stretch itself so that all the text fits inside only
           the area designated by the right and bottom lines (if included). If the
           padding lines are not included, Android uses the left and top lines to
           define this drawable area.
         </p>
         <p>To clarify the difference between the different lines, the left and top lines define
           which pixels of the image are allowed to be replicated in order to stretch the image.
           The bottom and right lines define the relative area within the image that the contents
           of the View are allowed to lie within.</p>
         <p>
           Here is a sample NinePatch file used to define a button:
         </p>
         <img src="../../../images/ninepatch_raw.png" alt="" />

         <p>This NinePatch defines one stretchable area with the left and top lines
           and the drawable area with the bottom and right lines. In the top image, the dotted grey
           lines identify the regions of the image that will be replicated in order to stretch the
image. The           pink
           rectangle in the bottom image identifies the region in which the contents of the View are
allowed.
           If the contents don't fit in this region, then the image will be stretched so that they
do.
</p>

<p>The <a href="../../../guide/developing/tools/draw9patch.html">Draw 9-patch</a> tool offers
   an extremely handy way to create your NinePatch images, using a WYSIWYG graphics editor. It
even raises warnings if the region you've defined for the stretchable area is at risk of
producing drawing artifacts as a result of the pixel replication.
</p>

<h3>Example XML</h3>

<p>Here's some sample layout XML that demonstrates how to add a NinePatch image to a
couple of buttons. (The NinePatch image is saved as
<code>res/drawable/my_button_background.9.png</code>
<pre>
&lt;Button id="@+id/tiny"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerInParent="true"
        android:text="Tiny"
        android:textSize="8sp"
        android:background="@drawable/my_button_background"/&gt;

&lt;Button id="@+id/big"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerInParent="true"
        android:text="Biiiiiiig text!"
        android:textSize="30sp"
        android:background="@drawable/my_button_background"/&gt;
</pre>
<p>Note that the width and height are set to "wrap_content" to make the button fit neatly around the
text.
</p>

<p>Below are the two buttons rendered from the XML and NinePatch image shown above.
Notice how the width and height of the button varies with the text, and the background image
stretches to accommodate it.
</p>

<img src="../../../images/ninepatch_examples.png" alt=""/>
    </div>

  <a href="#top" style="float:right">&uarr; Go to top</a>
  
    <p><a href="index.html">&larr; Back to Graphics</a></p>
  
  </div>

<div id="footer">


  <div id="copyright">
    
  Except as noted, this content is licensed under <a
  href="http://www.apache.org/licenses/LICENSE-2.0">Apache 2.0</a>. 
  For details and restrictions, see the <a href="../../../license.html">
  Content License</a>.
  </div>
  <div id="build_info">
    
  Android 4.0&nbsp;r1 - 17 Oct 2011 18:17

  </div>

  <div id="footerlinks">
    
  <p>
    <a href="http://www.android.com/terms.html">Site Terms of Service</a> -
    <a href="http://www.android.com/privacy.html">Privacy Policy</a> -
    <a href="http://www.android.com/branding.html">Brand Guidelines</a>
  </p>
  </div>

</div> <!-- end footer -->

</div><!-- end doc-content -->

</div> <!-- end body-content --> 

<script type="text/javascript">
init(); /* initialize android-developer-docs.js */
var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
var pageTracker = _gat._getTracker("UA-5831155-1");
pageTracker._trackPageview();
</script>

</body>
</html>



